The present invention is directed to ink compositions and ink jet printing. More specifically, the present invention is directed to ink compositions for ink jet printers. One embodiment of the present invention is directed to an ink composition consisting essentially of water, diethylene glycol-monobutyl ether (butyl carbitol), glycerol, an optional cyclohexyl pyrrolidinone component, a dye selected from the group consisting of dyes containing dansyl chromophores and dyes containing porphyrin chromophores, an optional biocide, and an optional polyalkylene oxide additive.
Ink compositions, especially those for use with ink jet printers, must satisfy a number of conditions in order to achieve acceptable printing.
The ink composition should possess properties which permit it to be jetted appropriately from an ink jet printer. In ink jet printing, droplets of ink are expelled from nozzles onto a recording medium. The ink should form a meniscus at each nozzle prior to being expelled in the form of a droplet. After a droplet is expelled, additional ink surges to the nozzle to reform the meniscus. Important properties of the ink in this context include the ink's viscosity and surface tension.
Generally, adjustment of the viscosity of an ink composition can negatively affect the print quality and/or drying time of the ink. Such adjustment may result in excessive feathering or wicking along the paper fibers as a result of capillary action, and longer drying times at higher viscosity. Adjustments to the surface tension to improve a certain characteristic of the ink may adversely affect other characteristics thereof.
In many applications, fast drying inks are desired. The drying time of an image can limit both the speed and the architecture of an ink jet printer. Faster drying inks allow one to design a faster printer without constraining its architecture. The drying characteristics of the ink should not be such that it dries in the nozzle of the ink jet printer, thus clogging the nozzle. However, slow drying inks have limited use in printers requiring high throughput.
Printing different colored inks next to each other often results in intercolor bleeding with conventional inks. Thus, it would be desirable if inks could be formulated which dried instantaneously to minimize intercolor bleeding. Accordingly, fast drying inks are particularly desirable in conjunction with color ink jet printers.
Drying time and print quality of an ink may be affected by the material on which the ink is applied. For example, paper is often sized with sizing components for the purpose of retarding or preventing penetration of liquids into the structure. Sizing is commonly done by introducing a material to the pulp during the paper making operation. Paper may be sized internally or on the surface. Acid sizing chemicals, such as Mon size available from Monsanto Chemical Company, or alkaline sizing chemicals, such as Hercon-76 available from Hercules Company, are precipitated onto the fibers primarily for the purpose of controlling penetration of liquids into the final dry paper. This process is known as internal sizing. Surface sizing entails the application of dispersions of film-forming substances such as converted starches, gums, and modified polymers to previously formed paper. Surface sizing imparts strength to the paper, and thus high quality printing papers are often surface sized as well. These and other materials tend to affect adversely the manner in which a particular ink dries.
As used herein, the term "plain paper" represents all standard office and xerographic paper except for photographic and thermal paper.
U.S. Pat. No. 4,838,938 (Tomida et al.) discloses a recording liquid comprising a special host molecule with inclusion ability, a dye, a liquid medium, a dispersing agent, a surfactant, a viscosity controller, and a surface tension controller. The liquid medium may comprise water and/or organic solvent. Organic solvents include isopropyl alcohol and N-methyl-2-pyrrolidone. The surfactant may comprise cationic, anionic, or nonionic surfactant. The viscosity controller may comprise polyvinyl alcohol, celluloses, water soluble resins, and the like. The surface tension controller may comprise diethanolamine, triethanol amines, and the like. A preferred viscosity at 25.degree. C. is 5 centipoise or less, more preferably 3 centipoise or less, with a surface tension of 35 to 65 dynes per centimeter.
U.S. Pat. No. 4,923,515 (Koike et al.) discloses an ink composition comprising water, an organic solvent, a dye, surfactants, viscosity controllers, and surface tension controllers. The organic solvents may comprise alkyl alcohols, amides, ketones or ketoalcohols, ethers, alkylene glycols, and the like.
U.S. Pat. No. 4,847,316 (Schick et al.) discloses an ink composition comprising a homogeneous blend of water dispersible polyurethane, water dispersible polyester, and a solvent system containing water or water admixed with a cosolvent. The cosolvent may include diethylene glycol monomethyl ether, diethylene glycol, n-propyl alcohol, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, and diethylene glycol monobutyl ether. Water comprises at least about 90.0 weight percent of the solvent system.
U.S. Pat. No. 4,150,997 (Hayes) discloses an ink composition for utilization in ink jet printing comprising an aqueous solution of a fluorescent pigment, a dye solubilizer, and butyl carbitol. The fluorescent pigment is a mixture of a dye and an organic resin. The butyl carbitol acts as a dye stabilizer and wetting agent.
U.S. Pat. No. 4,163,001 (Carumpalos et al.) discloses an ink composition comprising a laked alkali stable basic dye wherein the laking agent is dispersed in a liquid medium having butyl carbitol, water, a nonionic surfactant, and an amino alcohol.
U.S. Pat. No. 4,378,564 (Cross et al.) discloses an ink composition comprising water, dye, and glycol ether. The glycol ether may include butyl cellosolve (glycol monobutyl ether), butyl carbitol, and mixtures thereof.
U.S. Pat. No. 4,508,570 (Fujii et al.) discloses an aqueous ink component comprising a water-soluble dye, a polyhydric alcohol and/or an alkyl ether, water, and at least one water-soluble non-ionic surface active agent. The non-ionic surface active agent may comprise a polyoxyethylene alkyl ether.
U.S. Pat. No. 4,740,549 (Okuzono et al.) discloses a wipe-erasable ink composition for a writing board. The ink composition comprises a dye, an organic solvent, and a non-ionic surface active agent. The nonionic surface active agent may include polyoxyethylene sorbitol monostearate, polyoxyethylene oleyl ether, polyoxyethylene stearyl ether, and the like.
U.S. Pat. No. 4,889,877 (Seitz) discloses a printing ink composition comprising water, a non-volatile diluent, oil-containing microcapsules, a protective colloid blend, and a binder emulsion or alkali soluble resin. The non-volatile diluent may comprise methyl glucoside, dimethyl urea, sorbitol, erythritol, and polyoxyethylene polyols.
U.S. Pat. No. 4,836,852 (Knirsch et al.) discloses an ink composition comprising a dye in a mixture of water and glycol wetting agents. The dye may include solubilizing agents such as N-methyl pyrrolidone and derivatives thereof. A surface tension between 35 and 40 dynes per centimeter is disclosed.
U.S. Pat. No. 4,242,139 (Troster) discloses water-soluble dyestuffs of the formula ##STR1## in which Y is oxygen or an imino group, R.sup.1 and R.sup.2 are hydrogen, halogen or lower alkyl or lower alkoxy, n is 1 to 3, and Z is a cation. The dyestuffs are useful for fluorescent inks. The ink can also contain water miscible organic solvents such as glycerol or glycols and additives which are viscosity regulators and/or drying inhibitors, such as natural gums.
U.S. Pat. No. 4,243,694 (Mansukhani) discloses ink compositions suitable for ink jet printing by modulating the density of the applied jet by an electric field in accordance with the information to be recorded on metal, plastic, or paper surfaces, characterized by fluorescent properties in ultraviolet light, incorporating, in solution, a resin component, at least one solvent, proportioned to give the ink properties of heat and steam resistance, the inks being colorless in ordinary light and distinctly fluorescent in ultraviolet light so as to render them particularly suitable as a means for marking various materials whereby marking is normally invisible but easily detectable when subjected to ultraviolet illumination. The ink solvent may include aliphatic alcohol and other solvents which may be ketones, aldehydes, esters, ethers, glycols, glycol ethers, hydrocarbon, and lactones.
U.S. Pat. No. 4,153,593 (Zabiak et al.) discloses an aqueous jet printing ink composition which fluoresces under ultra violet radiation containing a water soluble fluorescent dye dissolved in the water base in an amount up to 2 percent by weight and a water soluble binder component dissolved in the water base in an amount to provide for a specific viscosity which does not exceed 20 centipoise and which preferably includes a fluorescent brightener alone or in combination with fluorescein or one of its salts. A humectant component may be added to the composition, which may include alkylene glycol and alkyl ethers of alkylene glycol.
U.S. Pat. No. 4,015,131 (McDonough et al.) discloses inks wherein the ordinary mixed light color of the ink is a color substantially different than the fluorescent color of the ink. Methods of use include detection of at least the fluorescent wavelength of the ink or detection of both the ink colors when irradiated for fluorescence and by exposure to mixed light.
Japanese Patent document 63-165470 discloses an ink jet ink comprising a water-soluble dye, a mixture of a specific polyhyric alcohol and specific derivatives thereof, a specific surfactant, and water at specific ratios. The polyhydric alcohol derivative is selected from mono, di, and triethylene glycol alkyl ethers and mono, di, and triethylene glycol alcohol ether acetates, such as diethylene glycol monobutyl ether. The polyhydric alcohol is selected from nono, di, tri, and tetrapolyethylene glycol, propylene glycol, and glycerol.
Japanese Abstract 93:134041t discloses water-based jet-printing inks which are fast drying and have good clogging resistance which contain water-soluble dye, a polyol derivative, and a surfactant. An example of an ink is diethylene glycol monobutyl ether, C.I. Acid Blue 22, sodium dodecylbenzenesulfonate, sodium dehydroacetate, and water.
U.S. Pat. No. 4,021,252 (Banczak et al.) discloses an ink composition suitable for ink jet printing on metal surfaces, the ink incorporating, in solution, a colorant, a resin component, an alcohol-water solvent, and optionally an electrolyte, proportioned to give the ink properties of low surface tension, low viscosity, and low resistivity, all these properties, together with the pH of the composition, being controlled to give excellent workability and stability of the ink in ink jet printing operations.
U.S. Pat. No. 4,793,860 (Murakami et al.) discloses an aqueous ink composition comprising a specific dye in an amount of 0.5 to 6.0 weight percent, in which 20 percent or more of the total of the cations of the --SO.sub.3 X and --OX groups directly connected to the aromatic rings of the dye are replaced by the Li.sup.+ ion or a quaternary ammonium ion, a polyhydric alcohol in an amount of at least 10 weight percent, and water.
Japanese Patent Publication 63-165470 discloses an ink composed of (1) a water-soluble dye, (2) a mixture of (a) a polyhydric alcohol derivative selected from the group of (mono, di, tri) ethylene glycol alkyl ethers and (mono, di, tri) ethylene glycol alcohol ether acetates, such as diethylene glycol monobutyl ether, and (b) a polyhydric alcohol selected from the group of (mono, di, tri, tetra, poly) ethylene glycol, propylene glycol, and glycerol, (3) a surfactant exhibiting a specific surface tension, and (4) water, all in specified amounts. The ink is usable without causing clogging of an ejection nozzle and has excellent quick-dryability and roundness of the printed dot.
U.S. Pat. No. 5,211,747 entitled "Ink Jet Ink Compositions Containing Desizing Agents," discloses an ink composition having a pH of about 5 to about 10 which contains a colorant, a liquid carrier, and less than about 5 percent by weight of a desizing agent. The desizing agent may be (1) poly(oxyalkylene) modified compounds of sorbitan esters, fatty amines, alkanol amides, castor oil, fatty acid, fatty alcohol; (2) hydrophilic poly(dialkyl-siloxanes); (3) fatty imidazolines; (4) fatty ester modified compounds of phosphate, sorbitan, glycerol, poly(ethylene glycol), sulfosuccinic acid, sulfonic acid, alkyl amine; (5) quaternary alkosulfate compounds; (6) poly(propylene oxide)-poly(ethylene oxide) copolymers; (7) poly(alkylene glycol); or (8) mixtures thereof.
Although known compositions and processes are suitable for their intended purposes, a need remains for improved ink compositions. In addition, a need remains for ink compositions exhibiting fast drying times and good print quality. There is also a need for fast drying ink compositions exhibiting high frequency responses. Further, a need exists for ink compositions exhibiting acceptable water fastness properties. Additionally, there is a need for ink compositions suitable for thermal ink jet printing processes which exhibit acceptable latency properties. A need also remains for ink compositions which are substantially colorless under ordinary viewing conditions which enable generation of concealed images. In addition, there is a need for ink compositions and printing processes that enable generation of images which are substantially colorless but detectable when exposed to radiation outside of the visible wavelength range. Further, there is a need for ink compositions that are invisible to the human eye under normal viewing conditions but readable by a sensor, such as an infrared detector or a fluorescence detector, or by the human eye under special viewing conditions such as illumination of the image with ultraviolet light. Additionally, there is a need for ink compositions that can provide a means for placing coded information on a document. There is also a need for ink compositions which exhibit rapid drying times on plain paper. In addition, there is a need for ink compositions which are suitable for annotating xerographic copies with markings not visible to the naked eye via a thermal ink jet printing process.